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Barotrauma: Major Challenge to Catch-and-Release

Barotrauma: Major Challenge to Catch-and-Release

Catch-and-release (C&R) has a hallowed history in North America, first gaining impetus among trout anglers in the 1930s, though in the 90 years since, there have been many challenges to its principles.

The Growth and Challenges of C&R

Famous fly fisherman Lee Wulff coined the phrase, “Gamefish are too valuable to be caught only once,” which became the rallying cry of C&R proponents. They emphasized the idea of fishing for fun, rather than for food and also noted the benefits to populations when fish are successfully released to grow and multiply.

This concept grew regionally among trout anglers and caught on in the 1970s among muskie anglers and in the bass world where tournaments adopted a release format, beginning in the 1970s. Among bass anglers, we’ve seen an excessive fixation on releasing bass, to the extent that subsistence anglers and kids who keep some bass for food have been criticized by self-proclaimed sportsmen. Fishery managers have noted this trend and tried to emphasize the biological benefits of moderate levels of harvest, which include thinning numbers of these prolific species to enhance growth rates and population structure.

While muskie anglers can be even more religious in their C&R attitudes than bass fishermen, dealing with these large, toothy fish as they thrash about with large treble-hook lures in the jaws can be problematic. Many less experienced anglers targeting muskies and big pike are intimidated, handling them poorly and releasing fish that can be highly stressed and damaged, leading to post-release mortality. Experience and education help inspire skill and confidence in this realm.

Anglers targeting walleyes, catfish, and panfish, species traditionally viewed as “food fish,” have been much slower to adopt C&R, either through regulations or voluntarily. Early on, representatives of commercial walleye fisheries fought what they saw as an attack on their traditions and economic base. And generations of anglers had a hard time releasing fish that are valued so highly as food. It took years and widespread implementation of slot limits to encourage release of walleyes, but today most avid anglers routinely release large fish voluntarily, keeping some smaller ones for a meal.

Biologists managing catfish and panfish have faced conflicting attitudes toward releasing fish, whether by regulation or voluntarily, that proved difficult to resolve. These challenges remain today, though fishery managers have come to view two schools of catfish anglers—those who fish for food and a different group who focus on catching very large catfish and releasing most of them. Researchers have identified various socioeconomic aspects of these divergent groups, and managers in several regions have been able to craft regulations that seem generally acceptable to both groups.

Adoption of C&R has proved most challenging among those who pursue panfish, arguably the most harvest-oriented of freshwater anglers. While minimum length limits for crappie have been accepted in many areas, fishermen generally seek the largest specimens to harvest. This attitude has been most problematic for bluegills, as research has shown that removal of disproportionate numbers of large males, in particular, can cause a cascading response whereby smaller and younger males mature and spawn, never fulfilling their growth potential. In addition, there are genetic components to growth potential, so the size structure on overharvested waterways may not improve without drastic management action.

Selective Harvest

In-Fisherman popularized the concept of “Selective Harvest,” beginning in 1986 with a series of articles by Editor In Chief Doug Stange who highlighted the benefits and drawbacks of C&R, including delayed mortality and a sociological shift away from using personally procured natural resources as food, an American tradition for centuries. Stange described Selective Harvest this way: “The fish we catch and keep to eat are for most of us a reward for our effort that goes beyond sport and ties us to the principle reason that our ancestors fished. Today, catching and then releasing fish so they can be caught again has become a vital part of fishing. In traditional fashion, however, most anglers still want to harvest at least some of their catch.


“Selective Harvest captures the best aspects of C&R on one hand and ‘catch and keep’ on the other. We suggest than anglers harvest fish selectively as a matter of conscience and conservation, and because fish are delicious, nutritious, and a renewable resource. Anglers release a portion of their catch, particularly large fish that are much less abundant than smaller ones of the same species. They release 3-pound bass in favor of keeping several 12-inch ones. Or they harvest a mess of abundant panfish of moderate size. This sustains good fishing while continuing a tradition of eating fish.” This philosophy has become the basis of novel regulations and voluntary conservation by today’s anglers.

A Philosophical Challenge

C&R found a divergent reception in Europe. In England and a few other realms, dedicated carp fishermen pay dearly for the right to fish a pond stocked with big fish. When they catch one, it’s treated with great care, as anglers even apply antiseptic solutions to the wound to promote healing. Yet in other countries, people have opposed voluntary release, believing that “using fish for sport” is cruel, while accepting commercial fishing and angler harvest. Animal-rights advocates succeeded in banning C&R in Germany in 1998, and Switzerland followed in 2009. In the U.S., similar activists have made news by rallying against sportfishing, as well as trapping, hunting, and other perceived animal abuses. They have sought to insert animal-rights material into educational curricula for youth, though polls suggest they haven’t made major inroads in altering the positive outlook of Americans toward sportfishing.


These challenges to C&R pale in comparison to one that anglers and fishery managers have generally “swept under the rug.” It’s barotrauma—the physiological damage to fish caught from deep water. In-Fisherman co-founder Ron Lindner relates a story from the early 1980s. Using a vintage flasher, he and brother Al found crappies suspended 30 feet down. “We were catching them one after the other,” Ron relates, “and releasing many. I looked around and said to Al, ‘We got a problem.’ Fish were floating, unable to swim down. This lesson was reinforced on a trip to Florida for red snapper where fish came up with stomachs protruding from the mouth, and with bulging eyes. Released fish struggled to swim down, but most floated into oblivion.”

“Floating” smallmouth bass. This live fish is unable to swim down or maintain a normal posture in the water due to an expanded gas bladder.

Barotrauma particularly affects species without a pneumatic duct connecting the esophagus and gas bladder, the organ that provides buoyancy. This feature allows many species, such as trout, salmon, char, carp, sturgeon, catfish, and others, to release gas from the bladder, which passes out the mouth.


When a fish is raised to the surface, the change in pressure causes gases in its body to expand. For a fish caught in 33 feet (one atmosphere), the volume required to contain the gas doubles. Because the gas bladder is elastic, it resists stretching, but gradually succumbs to pressure and expands, preventing fish from swimming back down. While immediate release from moderate depths (20 to 30 feet) typically causes minimal problems, holding a fish at the surface for several minutes makes successful release more difficult.

Keeping them in a livewell for hours causes severe symptoms, particularly as fish continually fight to submerge and to retain an upright posture, eventually wearing out. Anglers and local residents often report finding large numbers of dead fish that were released in a technically alive condition following tournament weigh-ins, but were soon overcome by a severe stress response, since stress reduces the rate at which fish can remove gas from their bladders in addition to its other debilitating effects.

The greater the depth, the more potential damage to blood vessels, eyes, and other tissues. I recall fishing for halibut in Alaska in several hundred feet of water about 15 years ago. While halibut lack a gas bladder and seem to be able to swim effortlessly back to the bottom, rockfish species inhabiting the same rocky structures are not so fortunate. These bass-shaped fish would fight for the first 70 or 80 feet off the bottom, then become dead weight as they perished on the ascent. While they’re wonderful table fare, the large adult rockfish of 5 to 10 pounds that we were catching are more than 60 years old and represent a population that won’t be replenished in our lifetimes. Barotrauma has recently become more of a threat, as modern anglers with large and luxurious boats, electronic GPS maps, and sophisticated sonar systems have been able to find and exploit fish populations on nearly every corner of the planet, at great depths.

Given the great popularity and economic value of recreational saltwater fishing, where many popular species inhabit water deeper than 60 feet, marine managers were way ahead of their freshwater colleagues in addressing this problem with lab and field studies. There have been dozens of scientific investigations of the physiology and management implications of barotrauma in marine species, mostly snapper, grouper, and rockfish, which are all extremely valuable to recreational anglers, commercial fishermen, and charter captains. And they often are managed with length limits that mandate release of many fish. A 2017 assessment by the National Oceanic and Atmospheric Administration estimated that 28.5 percent of recreationally caught red snapper and 38 percent of commercially caught fish died following release, and those levels were greatly exceeded by grouper catches.

The South Atlantic Fishery Management Council noted that improper release of unwanted fish was one of the most important problems facing fishery managers. In October 2019, the council thereby mandated that all commercial and recreational fishermen targeting grouper or snapper have a descending device to release fish on board and ready for use. Devices include weights that can be loosely clipped to the jaws of fish, and cages with a trap door that that can be triggered from the surface to hold a number of fish and return them to appropriate depths.

Before government turned to the COVID-19 outbreak, bipartisan legislation, the DESCEND Act, was making its way through Congress, which would require recreational and commercial fishermen in the Gulf of Mexico to have a descending tool rigged and ready to use. Products, such as SeaQualizer (, Rocklees Fish Descender (, and Shelton Fish Descender (, clip onto the jaw of a fish and carry it back down. The SeaQualizer is a sophisticated device with a release that’s triggered by water pressure, allowing the angler to set it for a particular depth. Anglers attach sinkers to the Rocklees and Shelton Descender to send fish down. Smaller versions of these devices would work for freshwater species.

In-Fisherman Contributor Ralph Manns has used this technique to descend largemouth bass back to depth. “The device I used (and still carry although I haven't fished deep enough to use it in years) was simply a 3-ounce flat, oval casting weight with a 4/0 barbless hook mounted so that it pointed down,” he says. “I would attach it to the swivel of my crankbait rod, stick it through the soft mouth tissues of a floating bass, and lower the fish and weight down at least 15 to 20 feet. The device would easily pull out the soft tissue when stopped, or a retrieve was started. The bass would swim away, re-compressed by water pressure. I still believe this to be a safer and easier procedure than fizzing for bass, but might not work well for release of multiple bass at tournaments.”


In the freshwater realm, anglers have been targeting fish aggregations in deep water more frequently, aided by sophisticated sonar units with powerful down-imaging, side-imaging, and 360-degree-imaging with amazing clarity. But outside of walleye and bass tournament anglers on deep waterways, few anglers learned to “fizz” fish using a hypodermic needle of approximately 18-gauge. Inserting the needle into the gas bladder lets air escape, allowing fish to descend. But needle placement must be precise or damage to other organs can occur. Physiological studies showed gas bladders healed quickly, but problems arose when many anglers stuck needles in the wrong locations, damaging other organs. As a result, some agencies discouraged or even banned “fizzing,” while others continue to allow or even recommend it.

Nearly all the information available to anglers in the popular freshwater fishing media is either incomplete or erroneous. For example, we still find the faulty advice to “reel fish from deep water up slowly to give them the opportunity to acclimate to gas expansion.” In truth the evacuation of excess gas from organs via the bloodstream takes hours.

At recent tournaments on the St. Lawrence River, on the border of New York and Canada, bass pros located groups of huge smallmouths more than 40 feet down. Several pros reported being shocked to see the many trophy-size bass floating later near the weigh-in site in New York. A 2008 study by Dr. Steven Cooke and Marie-Ange Gravel of Carleton University in Ontario examined a fall tournament on Rainy Lake, on the Minnesota-Ontario border. They found over 60 percent of a sample of smallmouth bass at the weigh-in showed signs of barotrauma—bloating, hemorrhaging, and loss of equilibrium. The worst cases were the largest bass. Forty percent of bass with severe symptoms died, though mortality for the whole event was 13 percent.

In other regions with deep reservoirs, particularly in the Southeast and West, anglers often target bass and other species deeper than 30 feet. Spotted bass in those waters are commonly caught in water over 50 feet deep during fall and winter there. Observation suggests some species are more vulnerable than others. Immediate release limits damage for spotted bass and smallmouths in particular.

Stange notes the apparent releasability of smallmouth bass in cold water. “Back in the 1970s right after ice-out I’d fish for smallmouths with jigs on West Okoboji in water from 20 to 30 over feet of water. In those days, we felt that if you caught a bass from the school and released it right away, you risked spooking the rest of them when it swam back down, either through the release of a chemical or by the way the released fish acted. So in those situations, I always put fish in the livewell until the school stopped biting, then released them. I don’t recall a fish that wasn’t releasable. I can also count on one hand the number of dead floating smallmouth I’ve seen over the years. Walleyes aren’t nearly as tolerant of pressure changes.”

"Floating” largemouth bass exhibiting barotrauma symptoms. The Texas Parks & Wildlife Department recently conducted a study on barotrauma at a bass tournament on Lake Amistad. Photo credit: Larry Hodge, TPWD

I’ve seen big largemouths caught in 22 to 25 feet at Lake Fork in Texas during fall floating upside-down in a livewell as we held them for a short time for improved photo conditions. Fizzing allowed them to finally descend. And in summer tournament conditions, I’ve seen smallmouths caught in similar depths and placed in livewells without fizzing turn belly-up after an hour or two, then be moribund several hours later at weigh-in.

As Ron and Al Lindner observed years ago in Canada, crappies are particularly vulnerable to even mild barotrauma, sometimes having difficulty swimming back down when caught and quickly released in less than 25 feet of water, a common occurrence in colder conditions. Anglers with underwater cameras have reported popular ice-fishing areas littered with the carcasses of fish that were released and didn’t survive, primarily due to barotrauma. Traditional release in those situations, whether by regulation or voluntary, wastes fish.

Angler opportunity and healthy fish populations are not only vitally important to millions of anglers, they represent a huge economic engine. According to recent statistics, America's anglers spend an estimated $49.8 billion per year in retail sales associated with fishing. With a total annual economic impact of $125 billion, fishing supports more than 800,000 jobs and generates $38 billion in wages and $16 billion in federal, state, and local taxes.

It’s important to maintain our momentum as recreational fishing continues to evolve and to promote sustainable practices. In this effort we need to further address the challenges presented by barotrauma to fishery management and healthy fish stocks. As noted earlier, marine fishery managers have been far more responsive to this issue, as it affects a major segment of popular fisheries in that realm. There’s even new legislation to promote and require use of descending devices. 

On the freshwater scene, we need to take a harder look at this problem, investigating reports of excessive mortality and discarded moribund fish in open-water and ice-fishing settings. It will require investigations into seasonal, geographic, and species-specific problem areas, as well as further physiological research and field investigations of the effects of pressure changes on fish. With this article, we hope to encourage angling organizations, fishery managers, media outlets, and manufacturers to work together to educate anglers about this challenge and to seek technological solutions, regulations, and new policies to maintain the health of fish populations for future generations.

*Steve Quinn is a former In-Fisherman Senior Editor and currently is a Field Editor and has written for In-Fisherman publications for over 30 years, as well as appeared regularly on In-Fisherman television. As a former state fishery biologist, he brings a unique perspective on all matters fishing and fish conservation.

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